How to grow climbing hydrangeas
All you need to know about growing climbing hydrangeas, including Hydrangea petiolaris, in this Grow Guide.
With their large, blowsy white flowers and attractive foliage, climbing hydrangeas are an excellent climbing plant for covering a shady north or east facing wall or fence, or even the wall of a house.
Hydrangea anomala subsp. petiolaris is the most common climbing hydrangea, with large white lacecap flowers in early summer and heart-shaped, dark green foliage that turns butter yellow in autumn. It's deciduous, which means it loses its leaves in winter after turning yellow in autumn, but is hardy and easy to grow. The Royal Horticultural Society has given it its prestigious Award of Garden Merit (AGM).
There are also two evergreen types of climbing hydrangea – Hydrangea seemannii and Hydrangea serratifolia. These need a sheltered, warm spot to thrive. Hydrangea seemannii comes from Mexico and has domed flower-heads of greenish-white flowers surrounded by white bracts. Hydrangea serratifolia hails from Chile and Argentina and has large, coarse leaves with panicles of creamy white flowers.
All climbing hydrangeas are vigorous plants, but can take several years to establish and flower. Give them plenty of room – Hydrangea petiolaris can reach an ultimate height and spread of 12m x 8m spread after 10-15 years, the evergreen varieties are slightly smaller at around 10m x 3m.
How to grow climbing hydrangeas
Grow Hydrangea petiolaris in moist but well-drained soil in shade or partial shade. Train the shoots initially onto galvanised wires or trellis along a wall or sturdy fence – after a season of growth they'll form self-clinging aerial roots. Do not allow the soil to dry out, especially in hot weather. Mulch annually in spring with well-rotted manure or compost. Prune after flowering in summer. Hydrangea seemannii and Hydrangea serratifolia need a sheltered, warm spot.
Climbing hydrangeas: jump links
- Planting climbing hydrangeas
- How to care for climbing hydrangeas
- How to propagate climbing hydrangeas
- How to prune climbing hydrangeas
- Climbing hydrangea problem-solving
- Varieties of climbing hydrangea to grow
More on growing hydrangeas
Where to plant climbing hydrangeas
Hydrangeas do best in dappled shade – not too sunny and not too shady. Hydrangea petiolaris will grow in sun, but the flowers won't last as long. Young growth is prone to frost damage in spring, so avoid planting in a frost pocket and plant away from strong winds.
Climbing hydrangeas will thrive in most soil types, including alkaline and acidic soil. However a moist, well-drained soil is ideal.
When to plant hydrangeas
The best time to plant hydrangeas is spring or autumn, when the soil is warm and moist. Planting in summer is doable, but you'll have to keep an eye on moisture levels in the soil.
How to plant Hydrangea petiolaris
The foliage of Hydrangea petiolaris can irritate the skin, so wear gloves when handling. Hydrangeas do well in moist soil, so if your soil is light, bulk it up with moisture-retaining organic matter such as well rotted manure or compost before planting. Water the plant well an hour or so before you plant it. Never plant a hydrangea deeper than it was in its original pot. Water in well. Mulch after planting, ideally with leaf mould – alternatively use well-rotted manure or compost. Keep the plant well watered throughout its first spring and summer.
You'll need to train Hydrangea petiolaris initially onto galvanised wires or trellis. After a season of growth it will make its own way as it will form self-clinging aerial roots but you will need to help them on their way. If you're growing plants along a fence, make sure it's sturdy – mature climbing hydrangeas are heavy. The arial roots of Hydrangea petiolaris should not damage a wall.
Where to buy Hydrangea petiolaris online
Caring for climbing hydrangeas
Mulch hydrangeas every year in spring, with leaf mould, well-rotted manure or compost. They don't need feeding, as this encourages leafy growth at the expense of flowers. Hydrangeas have a tendency to wilt in hot weather, and plants planted up walls are often in a 'rain shadow', which means that they don't get soaked when it does rain, so keep plants well watered during hot spells in summer.
How to prune Hydrangea petiolaris
Climbing hydrangeas are best pruned in summer, after flowering. Prune Hydrangea petiolaris lightly, as most flower buds are produced at the top of the plant. Cut back the flowered shoots to a pair of new buds. If your plant has grown too large, you may need to sacrifice the flowers for a few years by pruning back harder in autumn or spring.
Prune Hydrangea seemannii and Hydrangea serratifolia after they have flowered in summer, by trimming them to fit their space.
How to propagate Hydrangea petiolaris
The easiest way to propagate a climbing hydrangea is by layering it in spring. Identify a young, healthy branch that's dipping low or long enough to be pinned down to the ground. Using a knife or secateurs, clear the leaves from the stem and make a shallow cut on the stem, just below a bud on the newest wood. This will encourage it to root. Improve the soil with potting compost, then use a long hooked wire to pin the bare piece of stem down to the ground. Water the ground where you’ve pinned the stem and place a brick over the stem to ensure that it is stable for the growing season.
You can also propagate climbing hydrangeas by taking softwood cuttings in spring. In the morning look for young, non-flowering shoots that have three sets of leaves. For best results prepare cutting material straight away. Alternatively, keep them in a plastic bag in a cool shed. Remove the two sets of lower leaves and shorten the stem of the cutting. Cut just below a node. Insert the cuttings into a pot of cutting compost. More than one cutting can be placed in a pot as long as the leaves don’t touch. Water in and cover with a clear plastic bag. Ideally keep them in an unheated greenhouse. Once you see clear signs of growth pot on plants, keeping them in a shady spot.
Climbing hydrangeas: problem solving
If your plant doesn't grow much in the first few years, this is to be expected – the plant takes a while to get going. Poor growth could also be due to lack of water – climbing plants are often in a 'rain shadow' which means they do not benefit from rain when it falls, as it doesn't reach the base of the plant. Mulch the plant every spring to aid moisture retention in the soil and water in dry weather in summer.
Hydrangea petiolaris can take a few years to flower. Lack of flowers on a mature plant could be due to incorrect pruning. Climbing hydrangeas produce flowers on last year’s shoots, so in order for the plant to have enough time to develop flowering wood for the next year, prune in summer straight after flowering. Don't cut the plant back too much.
Brown spots on leaves
This is leaf spot, a fungal infection. It can occur when the weather is warm and moist and there's little air circulation. Remove any affected leaves as soon as you see them. Make sure you direct water the base of the plant when watering and if possible improve air circulation around it.
Brown blobs on leaves, poor growth
Hydrangea scale is a sap sucking insect found on hydrangeas. In severe cases it can cause poor growth and leaf loss. You may spot the eggs, covered in a white waxy material, in early summer. The mature scale insects look like brown blobs. If the problem is serious, spray in July with an organic insecticide based on plant oils or fatty acids. Otherwise birds and other predators will keep populations down naturally.
Advice on buying Hydrangea petiolaris
- Check that you have the right spot for a Hydrangea petiolaris – it will do best in dappled shade and moist soil
- Check that you have room for your plant – it will reach an ultimate height of 12m x 8m. It will need to be grown against a wall or sturdy fence
Where to buy Hydrangea petiolaris online
Varieties of climbing hydrangea to grow
Hydrangea anomala subsp. petiolaris is the standard climbing hydrangea, with dark green leaves and panicles of white flowers.
Height x Spread: 10m x 3m
Hydrangea anomala subsp. petiolaris 'Mirranda' is a variegated variety with cream or yellow edges to the leaves, and peeling brown bark. H x S: 12m x 8m
Hydrangea anomala subsp. petiolaris 'Silver Lining' – similar to the species but with silver variegation
H x S: 15m x 3m
Hydrangea anomala subsp. petiolaris 'Flying Saucer' has bigger flowers than the species, giving a stunning display.
H x S: 15m x 3m
Hydrangea seemannii has domed flower-heads of greenish-white flowers surrounded by white bracts.
H x S: 10m x 3m
Hydrangea serratifolia has large, coarse leaves with panicles of creamy white flowers.
H x S: 12m x 8m
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